This invention relates generally to the recovery of metallic particles at sub-surface localities, and more particularly concerns methods and apparatus for effecting such recovery without removal of the overburden and without mining activity carried out by humans at underground levels.
Mining operations over large areas of the world have involved stripping the overburden off bedrock underlying streams where gold and/or other precious metal particles were concentrated. Typically, intermixed soil and rocks were redeposited over the bedrock after dredging of the gold bearing layers; however, the bucket type dredging equipment that was conventionally employed could not reach much of the gold or metal particles, as for example larger particles that were trapped in cracks and crevices in the bedrock. Where ore recovery beneath the sea was conducted, ocean floor "sweeping operations" to recover loose particles and grannules did not contemplate recovery of inaccessible or trapped materials. No way was known, to my knowledge to accomplish recovery of such trapped precious metal particles, or other weight segregatable particles, in the simple manner as now afforded by the present invention. As to the latter, the invention is especially useful in that particle recovery may now be carried out beneath undisturbed land, without requiring stripping of the overburden off the bedrock.
Relevant patents are my U.S. Pat. Nos. 3,790,213 3,855,807; 3,856,355; and 3,917,326.